During certain surgical procedures, it may become necessary to separate adjacent tissue layers in order to create an internal surgical worksite. Various dissectors useful in the formation of such worksites are known, and typically include an expandable dissection element, e.g., a balloon, that is supported on the distal end of a tube. A need remains, however, for increased control over the expansion of such dissection elements in order to selectively limit tissue displacement during formation of the surgical worksite. The present disclosure addresses this need, among others, and describes a surgical apparatus including an expandable dissection element that allows for an increased level of control over expansion of the dissection element in one or more directions.